Editing Bally Astrocade (section)

== Specifications ==
[[File:Bally-Professional-Arcade-Deconstructed-01.jpg|thumb|Bally Astrocade motherboard]]

=== Circuit board and cartridges ===
* CPU: Zilog Z80, 1.789&nbsp;MHz
* RAM: 4 kB (up to 64 kB with external modules in the expansion port)
* ROM: 8 kB
* Cart ROM: 8 kB
* Expansion: 64 kB total
* Ports: 4 controller, 1 expansion, 1 light pen

=== Audio ===
[[File:Bally Arcade Tetris Theme Sound Chip Demonstration.ogg|thumb|Demonstration of Bally Arcade's multi-voice sound chip, including noise and various vibrato effects]]
*Sound chip model: 0066-117XX, also known as the [[Bally Astrocade Music Processor|Music Processor]],<ref name=":1">{{Cite web|url=https://ballyalley.com/documentation/misc_hardware_docs/Bally/full_size/Bally%20Arcade%20Service%20Manual%20(OCR).pdf|title=Bally Professional Arcade Service Manual|last=BALLY MANUFACTURING|website=ballyalley.com}}</ref> or a custom I/O chip<ref name=":1" /><ref name=":0">{{Cite web|url=https://raw.githubusercontent.com/mamedev/mame/master/src/devices/sound/astrocde.cpp|title=Source code for emulating the Astrocade custom "IO" chip in MESS/MAME|last=Giles|first=Aaron}}</ref> since the sound chip also performs I/O functions.
*Channel capabilities: There are 3 square wave channels, all with a pitch accuracy of 8-bits (256 possible frequencies from which to choose), which can all play square waves. The chip also has a noise generator, which can be independent from the other 3 square wave channels, or it can add its value to the master oscillator that drives the 3 square wave channels. The master oscillator can be set to different frequencies, which means that the frequency range can be changed for the 3 square wave channels.<ref name=":0" />
*Volume control: Each channel has independent 4-bit volume control.<ref name=":0" />
*Miscellaneous features concerning sound: There are hardware registers for vibrato, with two bits for the vibrato speed and 6 bits for vibrato depth.<ref name=":0" /> This means that it wouldn't be necessary for vibrato to be done entirely with software.

=== Video ===
*Resolution:     True 160×102 / Basic 160×88 / Expanded RAM 320×204
*Colors:         True 8* / Basic 2
**The bitmap structure of the Bally actually only allows for 4 color settings. However, through the use of 2 color palettes and a left/right boundary control byte you could have the left section of screen (this could be the play field) use 1 set of colors while the right side (this could show information such as lives and score) used an entirely different set of colors, thus 8 total colors were possible.
*Graphic type:   Bitmap, 2 bit per pixel bit map.